Michel Pleimling

University of Oxford, Oxford, England, United Kingdom

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Publications (114)199.91 Total impact

  • Source
    Ben Intoy, Michel Pleimling
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    ABSTRACT: We consider cyclic Lotka-Volterra models with three and four strategies where at every interaction agents play a strategy using a time-dependent probability distribution. Agents learn from a loss by reducing the probability to play a losing strategy at the next interaction. For that, an agent is described as an urn containing $\beta$ balls of three respectively four types where after a loss one of the balls corresponding to the losing strategy is replaced by a ball representing the winning strategy. Using both mean-field rate equations and numerical simulations, we investigate a range of quantities that allow us to characterize the properties of these cyclic models with time-dependent probability distributions. For the three-strategy case in a spatial setting we observe a transition from neutrally stable to stable when changing the level of discretization of the probability distribution. For large values of $\beta$, yielding a good approximation to a continuous distribution, spatially synchronized temporal oscillations dominate the system. For the four-strategy game the system is always neutrally stable, but different regimes emerge, depending on the size of the system and the level of discretization.
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    Nicholas Borchers, Michel Pleimling, R. K. P. Zia
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    ABSTRACT: The statistical mechanics of a one-dimensional Ising model in thermal equilibrium is well-established, textbook material. Yet, when driven far from equilibrium by coupling two sectors to two baths at different temperatures, it exhibits remarkable phenomena, including an unexpected 'freezing by heating.' These phenomena are explored through systematic numerical simulations. Our study reveals complicated relaxation processes as well as a crossover between two very different steady-state regimes.
    Physical Review E 11/2014; 90(6). DOI:10.1103/PhysRevE.90.062113 · 2.33 Impact Factor
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    James Mayberry, Keith Tauscher, Michel Pleimling
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    ABSTRACT: Synthetic antiferromagnets with strong perpendicular anisotropy can be modeled by layered Ising antiferromagnets. Accounting for the fact that in the experimental systems the ferromagnetic layers, coupled antiferromagnetically via spacers, are multilayers, we propose a description through Ising films where ferromagnetic stacks composed of multiple layers are coupled antiferromagnetically. We study the equilibrium and non-equilibrium properties of these systems where we vary the number of layers in each stack. Using numerical simulations, we construct equilibrium temperature$-$magnetic field phase diagrams for a variety of cases. We find the same dominant features (three stable phases, where one phase boundary ends in a critical end point, whereas the other phase boundary shows a tricritical point at which the transition changes from first to second order) for all studied cases. Using time-dependent quantities, we also study the ordering processes that take place after a temperature quench. The nature of long-lived metastable states are discussed for thin films, whereas for thick films we compute the surface autocorrelation exponent.
    Physical Review B 07/2014; 90(1). DOI:10.1103/PhysRevB.90.014438 · 3.66 Impact Factor
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    Ulrich Dobramysl, Michel Pleimling, Uwe C. Tauber
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    ABSTRACT: We study the pinning dynamics of magnetic flux (vortex) lines in a disordered type-II superconductor. Using numerical simulations of a directed elastic line model, we extract the pinning time distributions of vortex line segments. We compare different model implementations for the disorder in the surrounding medium: discrete, localized pinning potential wells that are either attractive and repulsive or purely attractive, and whose strengths are drawn from a Gaussian distribution; as well as continuous Gaussian random potential landscapes. We find that both schemes yield power law distributions in the pinned phase as predicted by extreme-event statistics, yet they differ significantly in their effective scaling exponents and their short-time behavior.
    Physical Review E 05/2014; 90(6). DOI:10.1103/PhysRevE.90.062108 · 2.33 Impact Factor
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    Matthew T. Shimer, Uwe C. Tauber, Michel Pleimling
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    ABSTRACT: We employ Monte Carlo simulations to investigate the non-equilibrium relaxation properties of the two- and three-dimensional Coulomb glass with different long-range repulsive interactions. Specifically, we explore the aging scaling laws in the two-time density autocorrelation function. We find that in the time window and parameter range accessible to us, the scaling exponents are not universal, depending on the filling fraction and temperature: As either the temperature decreases or the filling fraction deviates more from half-filling, the exponents reflect markedly slower relaxation kinetics. In comparison with a repulsive Coulomb potential, appropriate for impurity states in strongly disordered semiconductors, we observe that for logarithmic interactions, the soft pseudo-gap in the density of states is considerably broader, and the dependence of the scaling exponents on external parameters is much weaker. The latter situation is relevant for flux creep in the disorder-dominated Bose glass phase of type-II superconductors subject to columnar pinning centers.
    Physical Review E 03/2014; 90(3-1). DOI:10.1103/PhysRevE.90.032111 · 2.33 Impact Factor
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    Shahir Mowlaei, Ahmed Roman, Michel Pleimling
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    ABSTRACT: In order to model real ecological systems one has to consider many species that interact in complex ways. However, most of the recent theoretical studies have been restricted to few species systems with rather trivial interactions. The few studies dealing with larger number of species and/or more complex interaction schemes are mostly restricted to numerical explorations. In this paper we determine, starting from the deterministic mean-field rate equations, for large classes of systems the space of coexistence fixed points at which biodiversity is maximal. For systems with a single coexistence fixed point we derive complex Ginzburg-Landau equations that allow to describe space-time pattern realized in two space dimensions. For selected cases we compare the theoretical predictions with the pattern observed in numerical simulations.
    Journal of Physics A Mathematical and Theoretical 03/2014; 47(16). DOI:10.1088/1751-8113/47/16/165001 · 1.69 Impact Factor
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    Keith Tauscher, Michel Pleimling
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    ABSTRACT: We study the surface phase diagram of the three-dimensional kinetic Ising model below the equilibrium critical point subjected to a periodically oscillating magnetic field. Changing the surface interaction strength as well as the period of the external field, we obtain a non-equilibrium surface phase diagram that in parts strongly resembles the corresponding equilibrium phase diagram, with an ordinary transition, an extraordinary transition and a surface transition. These three lines meet at a special transition point. For weak surface couplings, however, the surface does not order. These results are found to remain qualitatively unchanged when using different single-spin flip dynamics.
    Physical Review E 02/2014; 89(2). DOI:10.1103/PhysRevE.89.022121 · 2.33 Impact Factor
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    Claude Godreche, Michel Pleimling
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    ABSTRACT: We consider the non-conserved dynamics of the Ising model on the two-dimensional square lattice, where each spin is influenced preferentially by its East and North neighbours. The single-spin flip rates are such that the stationary state is Gibbsian with respect to the usual ferromagnetic Ising Hamiltonian. We show the existence, in the paramagnetic phase, of a dynamical transition between two regimes of violation of the fluctuation-dissipation theorem in the nonequilibrium stationary state: a regime of weak violation where the stationary fluctuation-dissipation ratio is finite, when the asymmetry parameter is less than a threshold value, and a regime of strong violation where this ratio vanishes asymptotically above the threshold. The present study suggests that this novel kind of dynamical transition in nonequilibrium stationary states, already found for the directed Ising chain and the spherical model with asymmetric dynamics, might be quite general. In contrast with the later models, the equal-time correlation function for the two-dimensional directed Ising model depends on the asymmetry.
    Journal of Statistical Mechanics Theory and Experiment 01/2014; 2014(5). DOI:10.1088/1742-5468/2014/05/P05005 · 2.06 Impact Factor
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    Linjun Li, Michel Pleimling
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    ABSTRACT: Systems with a bulk first-order transition can display diverging correlation lengths close to a surface. This surface induced disordering yields a special type of surface criticality. Using extensive numerical simulations we study surface quantities in the two-dimensional Potts model with a large number of states $q$ which undergoes a discontinuous bulk transition. The surface critical exponents are thereby found to depend on the value of $q$, which is in contrast to prior claims that these exponents should be universal and independent of $q$. It follows that surface induced disordering at first-order transitions is characterized by exponents that depend on the details of the model.
    Physical Review B 11/2013; 88(21). DOI:10.1103/PhysRevB.88.214426 · 3.66 Impact Factor
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    Ben Intoy, Michel Pleimling
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    ABSTRACT: When four species compete stochastically in a cyclic way, the formation of two teams of mutually neutral partners is observed. In this paper we study through numerical simulations the extinction processes that can take place in this system both in the well mixed case as well as on different types of lattices. The different routes to extinction are revealed by the probability distribution of the domination time, i.e. the time needed for one team to fully occupy the system. If swapping is allowed between neutral partners, then the probability distribution is dominated by very long-lived states where a few very large domains persist, each domain being occupied by a mix of individuals from species that form one of the teams. Many aspects of the possible extinction scenarios are lost when only considering averaged quantities as for example the mean domination time.
    Journal of Statistical Mechanics Theory and Experiment 07/2013; 2013(08). DOI:10.1088/1742-5468/2013/08/P08011 · 2.06 Impact Factor
  • Hyunhang Park, Michel Pleimling
    Physical Review Letters 06/2013; 110(23). DOI:10.1103/PhysRevLett.110.239903 · 7.73 Impact Factor
  • Ahmed Roman, Debanjan Dasgupta, Michel Pleimling
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    ABSTRACT: In order to better understand the interplay of partnership and competition in population dynamics, we study a family of generalized May-Leonard models with N species. These models have a very rich structure, characterized by different types of space-time patterns. Interesting partnership formations emerge following the maxim that “the enemy of my enemy is my friend”. In specific cases cyclic dominance within coarsening clusters yields a peculiar coarsening behavior with intriguing pattern formation. We classify the different types of dynamics through the analysis of the square of the adjacency matrix. The dependence of the population densities on emerging pattern and propagating wave fronts is elucidated through a Fourier analysis. Finally, after having identified collaborating teams, we study interface fluctuations where we initially populate different parts of the system with different teams.
    Physical review. E, Statistical physics, plasmas, fluids, and related interdisciplinary topics 03/2013; 87(3). DOI:10.1103/PhysRevE.87.032148 · 2.33 Impact Factor
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    Hyunhang Park, Michel Pleimling
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    ABSTRACT: Using numerical simulations we investigate the properties of the dynamic phase transition that is encountered in the three-dimensional Ising model subjected to a periodically oscillating magnetic field. The values of the critical exponents are determined through finite-size scaling. Our results show that the studied non-equilibrium phase transition belongs to the universality class of the equilibrium three-dimensional Ising model.
    Physical review. E, Statistical physics, plasmas, fluids, and related interdisciplinary topics 03/2013; 87(3). DOI:10.1103/PhysRevE.87.032145 · 2.33 Impact Factor
  • Linjun Li, Michel Pleimling
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    ABSTRACT: Using extensive Monte Carlo simulations we study the properties of the non-equilibrium phase transition encountered in driven three-dimensional Potts systems with magnetic friction. Our system consists of two three-dimensional blocks, coupled through boundary spins, that move along their boundaries with a constant relative velocity. Changing the number of states in the system from two (Ising case) to nine states, we find different scenarios for the surface behavior depending on whether the bulk transition is continuous or discontinuous. In order to fully assess the properties of this non-equilibrium phase transition, we vary systematically the strength of the coupling between the two blocks as well as the value of the relative velocity. For strong couplings between the blocks the phase transition is found to be strongly anisotropic.
  • Nick Borchers, Michel Pleimling, R. K. P. Zia
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    ABSTRACT: From complex biological systems to a simple simmering pot, thermodynamic systems held out of equilibrium are exceedingly common in nature. Despite this, a general theory to describe these types of phenomena remains elusive. In this talk, we explore a simple modification of the venerable Ising model in hopes of shedding some light on these issues. In both one and two dimensions, systems attached to two distinct heat reservoirs exhibit many of the hallmarks of phase transition. When such systems settle into a non-equilibrium steady-state they exhibit numerous interesting phenomena, including an unexpected ``freezing by heating.'' There are striking and surprising similarities between the behavior of these systems in one and two dimensions, but also intriguing differences. These phenomena will be explored and possible approaches to understanding the behavior will be suggested.
  • James Mayberry, Michel Pleimling
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    ABSTRACT: Artificial antiferromagnets have attracted attention lately due to the potential for technological applications. We model these systems as thin Ising metamagnetic films and study their equilibrium properties using Monte Carlo simulations. In variance with previous work but in agreement with the experimental systems, we consider films comprised of ``sets'' of planes, with an antiferromagnetic coupling between sets and a ferromagnetic coupling within sets. This allows us to consider different situations by varying the number of planes in each set. Studying the magnetization density and response functions as a function of temperature and magnetic field, we determine the corresponding phase diagrams. We discuss how a change of the number of planes in each set changes the equilibrium phase diagram.
  • Hiba Assi, Ulrich Dobramysl, Michel Pleimling, Uwe Tauber
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    ABSTRACT: We investigate the non-equilibrium relaxation properties and steady states of interacting magnetic flux lines in type-II superconductors in the presence of driving external currents and / or different types and configurations of pinning centers. We model the vortices as elastic lines, and study the competing effects of thermal fluctuations, mutual repulsion, and pinning to defects. We employ both three-dimensional Monte Carlo and more efficient Langevin molecular dynamics simulations. Comparison of the resulting data for the non-equilibrium stationary states as well as the preceding relaxation regimes allows us to validate the utilization of both algorithms in out-of-equilibrium settings. We furthermore carefully analyze finite-size effects.
  • Ben Intoy, Sven Dorosz, Michel Pleimling
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    ABSTRACT: Although the mean-field solution for four species in cyclic competition is generally in good agreement with stochastic results, it fails to describe the extinction and absorbing states that finite size systems inevitably fall into. We study the effects of dimension, lattice type, and swapping rate between particles on the time it takes for the system to go into a static absorbing state, which consists of a neutral species pair. Lattice types discussed are the well mixed environment, the one-dimensional chain, the Sierpinski triangle, and the two-dimensional square lattice. Data presented were acquired with simulations that have around the order of a thousand lattice sites or less, to capture finite size effects. The formation of domains composed of neutral species yields long lived states which promote coexistence.
  • Ahmed Roman, Debanjan Dasgupta, Michel Pleimling
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    ABSTRACT: Understanding why and how species co-exist is a necessary step to the program of manipulating multispecies environments in order to preserve the biodiversity of the environment of interest. To this end we consider a generalization of the cyclic competition of species model. We show that our model enjoys a Zn symmetry which is explained via a simple graph theoretic technique. This symmetry gives rise to pattern formation and cluster coarsening of the species. We show that biodiversity is achievable in the mean field limit provided that the species in the clusters have reaction rates which correspond to non-trivial equilibria.
  • Source
    Nickolas Gray, Djordje Minic, Michel Pleimling
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    ABSTRACT: In this article we review the relation between string theory and non-equilibrium physics based on our previously published work. First we explain why a theory of quantum gravity and non-equilibrium statistical physics should be related in the first place. Then we present the necessary background from the recent research in non-equilibrium physics. The review discusses the relationship of string theory and aging phenomena, as well as the connection between AdS/CFT correspondence and the Jarzynski identity. We also discuss the emergent symmetries in fully developed turbulence and the corresponding non-equilibrium stationary states. Finally we outline a larger picture regarding the relationship between non-perturbative quantum gravity and non-equilibrium statistical physics. This relationship can be understood as a natural generalization of the well-known Wilsonian relation between local quantum field theory and equilibrium statistical physics of critical phenomena. According to this picture the AdS/CFT duality is just an example of a more general connection between non-perturbative quantum gravity and non-equilibrium physics. In the appendix of this review we discuss a new kind of complementarity between thermodynamics and statistical physics which should be important in the context of black hole complementarity.
    International Journal of Modern Physics A 01/2013; 28(7). DOI:10.1142/S0217751X13300093 · 1.09 Impact Factor

Publication Stats

1k Citations
199.91 Total Impact Points

Institutions

  • 2014
    • University of Oxford
      Oxford, England, United Kingdom
  • 1970–2014
    • Virginia Polytechnic Institute and State University
      • Department of Physics
      Blacksburg, Virginia, United States
  • 2011
    • Clarkson University
      • Department of Physics
      Potsdam, NY, United States
  • 2009
    • National Institute for Theoretical Physics
      Stellenbosch, Western Cape, South Africa
  • 2000–2007
    • Friedrich-Alexander Universität Erlangen-Nürnberg
      • Institute of Theoretical Physics
      Erlangen, Bavaria, Germany
  • 2006
    • University of Florence
      Florens, Tuscany, Italy
  • 2005
    • Universität Stuttgart
      • Institute of Theoretical Physics
      Stuttgart, Baden-Württemberg, Germany
    • Bielefeld University
      Bielefeld, North Rhine-Westphalia, Germany
  • 2001–2005
    • Universitätsklinikum Erlangen
      Erlangen, Bavaria, Germany